Answer:
a. x increased by three
Explanation:
An equation has to have an equal sign.
The word "is" usually means "equals", and an equal sign is used for it.
Look at the choices:
a. x increased by three -------> no word is; expression; x + 3
b. Seven more than m is 15 ----> equation; m + 7 = 15
c. Three minus five is -2 ----> equation; 3 - 5 = -2
d. Twelve is half a number ------> equation; 12 = 1/2 × n
The first choice is an expression, not an equation.
the last three choices are equations.
Answer: a. x increased by three