Number : A number $x$ is a mathematical symbol representing a quantity.

Look at the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

The correct answer is 2. The number directly before 3 is 2.

Squared : $x$ squared refers to the number $x^2=x\cdot x.$ For example 3 squared equals 9.

$1^2=1\cdot1.$

The correct answer is 1. $1^2=1\cdot1=1$

Addition : Addition is the mathematical operation that describes increasing a number by an amount equal to a second number. The mathematical symbol for addition is the plus sign $+.$ The term addition is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Equation : An equation is a mathematical statement in which two expressions are written with an equal sign in between. A solution of an equation is a set of variables that makes the statement a true statement.

Expression : An expression is a succession of constants, variables and mathematical operations that if evaluated for specific values of the variables represents a number.

Linear equation : A linear equation is an equation that is equivalent to the equation $mx+b=0.$ A linear equation with $m\neq 0$ has exactly the solution $x=\frac{-b}{m}$

Multiple : A multiple of a number $x$ is any of the numbers $1x,2x,3x,4x,\ldots.$ For example the multiples of 7 include 7, 14, 21 and 70.

Multiplication : Multiplication is the mathematical operation that is a shorthand for adding the same amount several times. For example $3\cdot 4=4+4+4=12.$

Solution : A solution to an equation is a choice of variables that when substituted into the equation results in a true statement.

Substitution : A substitution is replacing a term or variable with another term or variable. For example when solving a two-dimensional linear equation, one can solve the first equation for one variable and then substitute that expression for that variable in the second variable to get a linear equation only involving one variable.

Subtraction : Subtraction is the mathematical operation that describes decreasing a number by an amount equal to a second number. The mathematical symbol for subtraction is the minus sign $-.$ The term subtraction is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Variable : A letter in an expression or function that represents an arbitrary number.

Solve either equation for $x$ or $y$ and substitute the resulting expression into the second equation. You can also multiply one of the equations by some multiple and then add or subtract the resulting equation to/from the other equation trying to generate an equation that has only one of the variables $x$ or $y$ in it. Then solve this linear equation with one variable.

The correct answer is 1,2. We can verify that $x=1$ and $y=2$ solve both equations simultaneously: $2\cdot1+1\cdot2=4$ and $3\cdot1-3\cdot2=-3.$