Answer :
write an equation
10 + 3x = 15 +2x
-2x -2x
-----------------------
10 + x (1x) = 15
-10 -10
----------------------
x = 5
cost= 25 (10 + 15)
10 + 3x = 15 +2x
-2x -2x
-----------------------
10 + x (1x) = 15
-10 -10
----------------------
x = 5
cost= 25 (10 + 15)