John and Sara worked 20 hours at their job. John worked 2.5 more hours then Sarah. Write an expression that for both john and sara.

Question

Write any equation to express how many hours both john and sara worked.

Answer 1

Thank you for posting - there are 2 expressions that need to written, and then combined and solved...this is called "System of Equations"

 

The first equation expresses their combined hours worked. Let "J" be the number of hours John worked, and "S" be the number of hours Sarah worked. They worked a combined 20 hours, so the first equation is

 

S + J = 20

 

The next equation compares the number of hours each one of them worked...John worked 2.5 more than Sarah, so the second equation would be

 

J = 2.5 + S

 

You can combine them by substitution...so in the first equation, instead of "J" you would write "2.5 + S" and get

 

S + 2.5 + S = 20

 

Combine like terms and solve for "S"

 

2S + 2.5 = 20

 

2S = 17.5

 

S = 8.75

 

Plug 8.75 back into either of the 2 equations for "S" (I chose the 1st one) and solve for "J"

 

J + 8.75 = 20...so we get that J = 11.25

 

Let's double check the first equation...S + J = 20...8.75 + 11.25 = 20. WORKS!

 

Let's double check the second equation...J = 2.5 +S.... 11.25 = 2.5 + 8.75 WORKS!