A+b=13
a-b=7
add the two equations using system of equations
2a=20
a=10
10+b=13
b=3
Answer:

Step-by-step explanation:
The question in English
1.5 hours for tuning; 0.2 hours for cleaning the battery; 0.75 hours for changing the oil and engine filter; 1.45 hours for changing and aligning lights; and 1.3 hours for repairing the air conditioning system. The hourly rate is 32.8 soles; how much does it cost to repair the car?
step 1
Sum the hours to repair the car

step 2
Find the cost
Multiply the total hours by
so

use 
to get 
then use
and 
also, 
to get 
then again use the first identity In both pairs, i.e.

to get 
multiply and divide by 4 to get the RHS.
because, 
squaring both sides, 
Slope = 20/6 = 10/3
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