Put into mathematical equation: one fifth the sum of 7 and a number

(x+7)·.2

Step-by-step explanation:

The sum of x and 7 is x+7. The word sum indicates addition. Then it says multiply by 1/5, so i converted it to decimal which is .2

i think asking google will you get the answer to that question

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18