Sumalee was going to sell all of her stamp collection to buy a video game. After selling half of them she changed her mind. She then bought 14 more. How many did she start with if she now has 35?

42

Step-by-step explanation:

subtract 14 from 35

multiply by 2

basically reverse every operation performed

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