Question

Raymond wanted to buy 8 t-shirt but he was short of $8.10. instead he bought 5 T-shirt and had $12.60 left. how much would he need to pay for 20 t-shirt?

Answer 1

$138

Explanation:

Let the money with Raymond be $y

Let the cost of 1 tshirt be $x

then cost of 8 tshirt = cost of 1 t-shirt*8 = 8x

Raymond wanted to buy 8 t-shirt but he was short of $8.10

It means that 8x is equal to money he had plus $8.10

thus,

y + 8.10 = 8x

y = 8x - 8.10

Next situation

cost of 5 t-shirt = 5x

. instead he bought 5 T-shirt and had $12.60 left,

it means cost of 5 T-shirt plus $12.60 = total money Raymond had

y = 5x + 12.60

comparing y in both the equation

y = 8x - 8.10 and y = 8x - 8.10

5x + 12.60 = 8x - 8.10

=> 8x-5x = 12.60+8.10

=> 3x = 20.70

=> x = 20.70/3 = 6.9

Thus, cost of 1 T-shirt = $6.9

cost of 20 T-shirt = 20*$6.9 = $138 (Answer)