Step-by-step explanation: To evaluate an expression means simplifying it down to a number and usually you will be given variables to substitute in and evaluate.
For example, let's evaluate the expression 3y + 7 when y = 2.
We simply multiply 3 x 2 and add 7 or 3(2) + 7.
3 x 2 is 6 so we have 6 + 7 which is 13.
