My teacher always told me: use the percent change formula!!!
Here it is: new value-old value/ old value * 100%
This strategy will ALWAYS work for percent increase AND decrease: let's try it on this problem!
56700-42000/42000 * 100%
14,700/42000 = 100(x)
100* 14700 = 1470000
1470000/42000= 35
35/100 = 35%
Therfore, our percent increase is 35%!