Question

Bruce bought two books. one book cost four dollars more than three times the other. together the two books cost him $72. Answer using symbolic language

Answer 1

Cost of one book = $61

and cost of another book =$17

Explanation:

Let the cost of one book be x and cost of another book be y.

According to given problem,

x = 3y+4 {one book cost four dollars more than three times the other}

And x + y =72 {two books cost $72}

So we got two equations:

x = 3y+4 -------------(1)

x + y = 72 ---------------(2)

Subtract equation (1) from (2)

i.e x + y - x = 72 - 3y -4

or y = 68 - 3y

or y +3y =68

or y =
`(68)/(4)`

or y = 17

Then x = 3y + 4 = 3×19 + 4 =61

Hence we got, cost of one book = x =$61

Cost of another book = y = $17