10)
variable : cost of 1 square foot flooring = x
equation :
60x + 80 = 287
60x = 287 - 80
x = (287-80) / 60
11)
variable : doughnut cost = d
equation :
3(1.25) + 6d = 6.90
3.75 + 6d = 6.90
6d = 6.90 - 3.75
d = (6.90 - 3.75) / 6
12)
variable : smaller number = x
equation :
x + x + 1 = -29
2x + 1 = -29
2x = -29 - 1
x = (-29 - 1) / 2
13)
variable : number of shrubs : n
eqution :
n(25) + 110 = 260
25n = 260 - 110
n = (260 - 110) / 25
