The easiest way is to use (& to memorize) the sum formula for a AP:
Sum = 1st term added to the last term & multiplied by half the number of terms
S = (a+l)n/2
S = (5 + 53)(7/2) = 203
George completed more homework than Tina. Two thirds is equall to 66%
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The answer is: x = 10, y = 2
Leave a thanks because your welcome :)
Work:
x + y = 12
(10) + (2)+ = 12
Correct
x - 2y = 6
(10) - 2(2) = 6
10 - 4 = 6
Correct