Solve by substitution

Question

Solve by substitution:  2x +5y=23

                                 y=3x + 8

Answer 1

Jerica,

 

Since y = 3x+8, you can substitute 3x+8 for y in the first equation

 

2x+5y=23

 

2x + 5(3x+8) = 23

2x + 15x + 40 = 23

 

Combining terms

17x + 40 - -23

17x = -17

x = -1

 

And since y = 3x+8

y = 3(-1) + 8

y = -3+8

y = 5

 

x = -1

y = 5