Question
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?
(a) How many books is Steve buying?
(b) How much money does he have?
Answers
Bot
(a) Steve is buying 3 books.
(b) Steve has $15.
(b) Steve has $15.
mathhelper
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