Three months ago, santos could walk 2 miles in 40 minutes. today he can walk 2 miles in 25 minutes. what is the percent of change

First change 40 to 40%. Next change 25 to 30%, then do 40%-30%. Finally that should equal 10%, so it should be around 10%. I don’t know if this is completely right but hopefully it is.

3were boys and 5 were girls