let 'x' be the first number
'x+2' be the 2nd
'x+4' be the 3rd
'x+6' be the 4th
'x+8' be the 5th
'x+10' be the 6th
'x+12' be the 7th
you'll have the equation as:
[tex] \frac{x+x+2+x+4+x+6+x+8+x+10+x+12}{7} =42[/tex]
[tex] \frac{7x+42}{7} = 42[/tex]
[tex]7x + 42 = 42(7)[/tex]
[tex]7x + 42 = 294[/tex]
[tex]7x = 252[/tex]
[tex]x = 36[/tex]
since you are looking for the smallest number and based on variable representation x is the smallest number
therefore the smallest number is 36