140 for 21 minutes how much for 18.minutes
1 answer:
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Answer:
(8,-1)
Step-by-step explanation:
Given :
To Find: solution of given system of equations.
Solution:
Equation a :
Equation b :
Substitute the value of y from equation b in equation a
y from equation b : y = 7-x
Now substitute value of y in equation a
Thus equation a becomes:
⇒ x= -1 and x = 8
Now substitute values of x in equation b to obtains values of y
⇒
for x = -1
⇒
⇒
⇒
Thus (x,y)=(-1,8)
For x =8
⇒
⇒
⇒
Thus (x,y)=(8,-1)
Hence Option A is the correct solution .