Step 1)* Solve the second equation for #y#:
#y + 4 = 5x#
#y + 4 - color(red)(4) = 5x - color(red)(4)#
#y + 0 = 5x - 4#
#y = 5x - 4#
Step 2) Substitute #(5x - 4)# for #y# in the first equation and solve for #x#:
#3x + y = 1# becomes:
#3x + (5x - 4) = 1#
#3x + 5x - 4 = 1#
#(3 + 5)x - 4 = 1#
#8x - 4 = 1#
#8x - 4 + color(red)(4) = 1 + color(red)(4) #
#8x - 0 = 5#
#8x = 5#
#(8x)/color(red)(8) = 5/color(red)(8)#
#(color(red)(cancel(color(black)(8)))x)/cancel(color(red)(8)) = 5/8#
#x = 5/8#
**Step 3)# Substitute #5/8# for #x# in the solution to the second equation at the end of Step 1 and calculate #y#:
#y = 5x - 4# becomes:
#y = (5 xx 5/8) - 4#
#y = 25/8 - 4#
#y = 25/8 - (8/8 xx 4)#
#y = 25/8 - 32/8#
#y = (25 - 32)/8#
#y = -7/8#
The Solution Is: #x = 5/8# and #y = -7/8# or #(5/8, -7/8)#