We can check by subbing in the values.

7x + 2y = -7
(7,9).....x = 7 and y = 9
now we sub
7(7) + 2(9) = -7
49 + 18 = -7
67 = -7 (incorrect)....therefore, (7,9) is NOT a solution for this equation

8 0

3 years ago

When 2/3 of a number is increased by 20, the sum is then halved, the result obtained is the same as 2/3 of the number, increased

aleksklad [387]

$\frac{2/3x+20}{2} =\frac{2}{3} x+3\\\frac{2/3x+20}{2} - 3 = \frac{2}{3}x\\\frac{2/3x+20}{2} - \frac{6}{2} = \frac{2}{3}x\\\frac{2/3x+20-6}{2} = \frac{2}{3}x\\\frac{2/3x+14}{2} = \frac{2}{3}x\\2(\frac{2/3x+14}{2}) = 2(\frac{2}{3}x)\\2/3x+14=\frac{4}{3}x\\14=\frac{4}{3}x-\frac{2}{3}x\\14=\frac{2}{3}x\\\frac{14}{1}/\frac{2}{3}=x\\\frac{14}{1}*\frac{3}{2}=x\\7*3=x\\x=21$

The number is 21.

4 0

3 years ago