(a) Steve is buying 3 books.
(b) Steve has $15.
A math book costs $9 and a science book costs $7. If Steve spends all his money in the science books, he still has $6 left. However, if he buys the same number of math books, he needs another $8 more.
(a) How many books is Steve buying?
(b) How much money does he have?
2 answers
Where are these answers coming from, and who is answering them????
Suppose he has $M, and he buys x books
M - 7x = 6
M - 9x = -8
subtract these
2x = 14
x = 7
M - 49 = 6
M = 55
So he has $55, and he buys 7 books
check: to buy 7 science books would cost $49 leaving him with $6, check!
to buy 7 math books would cost $63 , leaving him $8 short
Suppose he has $M, and he buys x books
M - 7x = 6
M - 9x = -8
subtract these
2x = 14
x = 7
M - 49 = 6
M = 55
So he has $55, and he buys 7 books
check: to buy 7 science books would cost $49 leaving him with $6, check!
to buy 7 math books would cost $63 , leaving him $8 short
1 answer