It works because 7 x 9 x 10 is the same thing as 7 x 90, since 9 x 10 is just 90. So basically he is just writing more but the answer will still be the same.
Answer:
<u><em>note:</em></u>
<u><em>solution is attached in word form due to error in mathematical equation. furthermore i also attach Screenshot of solution in word due to different version of MS Office please find the attachment</em></u>
Answer:
5x + 6y = 20_____(1)
8x - 6y = -46_____(2)
Solving simultaneously:
Eqn(1) + Eqn(2)
5x + 8x + 6y + (-6y) = 20 + (-46)
13x = -26
x = -2
substituting this into Eqn (1):
5(-2) + 6y = 20
-10 + 6y = 20
6y = 30
y = 5
hence:
x = -2,y = 5.
