Both of these lines share the relationship together of being parallel.
X = dull pencils
y = sharp pencils
x + y = 100
y = x + 16 ~~Plug this back into your original x+y equation.
x+x+16=100 ==> 2x = 84 ==> x = 42. Plug this back into the y = equation
y = 42 + 16 ==> y = 58.
42 Dull, 58 sharp.
