T= 21.79x + 3.99x + 6.89x where t is the total cost and x is the number of brushes/rollers/paint cans you buy. You don't need a different variable for each item because you buy the same amount of each.
1250x.08= 100+1250= 1350 / 120 is 11.25 so 11 months of paying $120 leaves a $30 12th month payment.
If the weight of the little brother is x, then the weight of Charles is x + 9
The equation that can be used to determine what each one weighs is:
x + (x + 9) = 99.
Let us now solve it.
x + x +9 = 99
2x + 9 = 99
2x = 99 - 9
2x = 90
x = 90/2
x = 45
Little brother's weight is 45 kg.
Charles' weight will be 45 + 9 = 54 kg
Adding these two weights will give 99kg
