Question

Giselle works as a carpenter and as a blacksmith. She earns $20\$20 $20 dollar sign, 20 per hour as a carpenter and $25\$25 $25 dollar sign, 25 per hour as a blacksmith. Last week, Giselle worked both jobs for a total of 3030 30 30 hours, and earned a total of $690\$690 $690 dollar sign, 690 . How long did Giselle work as a carpenter last week, and how long did she work as a blacksmith? Giselle worked as a carpenter for hours and as a blacksmith for hours last week.

Answer 1

C = # of carpenter hrs , b = # of blacksmith hrs

c + b = 30...c = 30 - b
20c + 25b = 690

20(30 - b) + 25b = 690
600 - 20b + 25b = 690
-20b + 25b = 690 - 600
5b = 90
b = 90/5
b = 18 <== hrs worked as blacksmith

c + b = 30
c + 18 = 30
c = 30 - 18
c = 12 <== hrs worked as carpenter