Question 1052319
3x+2y = 12 (1)
1x+3y = 11; 1x is the same as just x, so
x+3y = 11 (2)
Multiply both sides of (1) times 3 and both sides of (2) times 2:
9x+6y = 36 (3)
2x+6y = 22 (4)
Now subtract (4) from (3):
9x+6y = 36
-
2x+6y = 22
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7x+0y = 14 
and here 0y means we don't have any y because 6y-6y=0, so we re-write:
7x = 14 divide both sides by 7
x = 2 This is the cost of a pen
and
x+3y = 11
2+3y = 11
3y = 9
y = 3 This is the cost of a notebook
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Check:
3x+2y = 12; 3(2)+2(3) = 12; 6+6 = 12 Correct
x+3y = 11; 2+3(3) = 11; 2+9 = 11 Correct
:
John