Let #x# be the first angle.
The second angle is #10°# less than four times the first.
In terms of #x#, the second angle is:
#4x - 10#.
We're told that the sum of the two angles is #180°#.
This can now be written as the equation:
#180 = x + 4x - 10#
Solve for x:
#180 = 5x - 10#
#x = (180+10)/5#
#x = 38°" "# (this is our first angle)
Since we already have an expression for our second angle in terms of #x#, we can simply substitute this value to find the second angle:
#4x - 10#
#=4(38) - 10#
# = 142°" "# (second angle)
