\left\{ \begin{array} { l } { 0.77 \times 100 + x = 5 } \\ { x + y = 1500 } \end{array} \right.
Solve for x, y
x=-72
y=1572
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x+77=5,x+y=1500
To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.
x+77=5
Pick one of the two equations which is more simple to solve for x by isolating x on the left hand side of the equal sign.
x=-72
Subtract 77 from both sides of the equation.
-72+y=1500
Substitute -72 for x in the other equation, x+y=1500.
y=1572
Add 72 to both sides of the equation.
x=-72,y=1572
The system is now solved.
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