Kirk just started a new job that pays $7 per hour. he had been making $5 per hour at his old job. Kirk worked a total of 54 hours last month and made $338 before deductions. How many hours did he work at his new job?
2007-03-08 10:44:56 · 3 answers · asked by ymeseventeen 1 in Science & Mathematics ➔ Mathematics
You'll need a system of equations to solve this one.
Let x = the number of hours worked at his old job ($5)
Let y = the number of hours worked at his new job ($7)
He worked a total of 54 hours last month, so
x + y = 54
He made $338, so
5x + 7y = 338
Solve the system by your favorite method. I'll use substitution here.
x = 54 - y (solve for x)
5(54 - y) + 7y = 338 (substitute)
270 - 5y + 7y = 338 (distribute)
270 + 2y = 338 (combine like terms)
2y = 68 (subtract 270 from both sides)
y = 34 (divide both sides by 2)
Kirk worked 34 hours at his new job (and 20 hours at his old one).
Check your work: 5 * 20 = 100 and 7 * 34 = 238. Add the two together, and voila... $338! :)
2007-03-08 10:54:01 · answer #1 · answered by yanksfan 2 · 1⤊ 0⤋
Set up 2 eqns with what you know: (x = hours @ 5/hr, y = hours @ 7/hr)
5x + 7y = 338
x + y = 54 â x = 54-y
Eq 1 becomes 5(54-y) + 7y = 338 â y = 34hr
2007-03-08 10:56:22 · answer #2 · answered by Steve 7 · 0⤊ 0⤋
Uh, trick question- 54 hours
2007-03-08 10:52:04 · answer #3 · answered by Shay-la♥ 3 · 0⤊ 0⤋