Mean is he meanest one because you have to do the most work. Add up all of the numbers and divide by the quantity of numbers.
Tyler: (142 + 123 + 141 + 156 + 189 + 174 + 196 )÷ 7 = 1121/7 ≈ 160
Brandon: 136 + 136 + 185 + 147 + 169 + 185 + 124 ÷ 7 = 1082/7 ≈ 155
a) Tyler had a higher average
b) there was a difference of 5 between their averages