5(a + b) + 21 for a=15 and b=27
5(15+b)+21=75+5b+21=96+5b=5b= -95b= -19 1/55(a+27)+21=5a+135+21=5a+156=5a= -156a= -31 1/55(15+27)+21=75+135+21=231
\(5(a + b) + 21\) \(5(a(15) + b) + 21\) \(Substitute \ a \ for \ 15\) \(5(a(15) + b(27)) + 21\) \(Substitute \ b \ for \ 27\) \(5(15 + 27) + 21\) \(5*42+21\) \(210+21\) \(= 231\)
