How long did Giselle work as a carpenter last week, and how long did she work as a blacksmith?

Question

She earns \$20$20dollar sign, 20 per hour as a carpenter and \$25$25dollar sign, 25 per hour as a blacksmith. Last week, Giselle worked both jobs for a total of 303030 hours, and earned a total of \$690$690dollar sign, 690.
How long did Giselle work as a carpenter last week, and how long did she work as a blacksmith?

Answer 1

$20/hr carpenter pay

$25/hr blacksmith pay

 

Let c = hours working carpentry

Let b = hours working as blacksmith

 

c + b = 30   {equation 1}

20c + 25b = 690   {equation 2}

 

In equation 1 solve for one variable in terms of the other.

c = 30-b

Substitute that into equation 2:

 

20(30-b) + 25b = 690

600 - 20b + 25b = 690

5b = 90

b = 90/5

b = 18 hours working as a blacksmith

 

c = 30-b = 30-18 = 12 hours as a carpenter

 

Questions?