If you would like to know how many passes has John attempted this year, you can calculate this using the following steps:
70% of x passes = 35 passes
70% * x = 35
70/100 * x = 35 /*100/70
x = 35 * 100/70 = 35 * 10/7
x = 50 passes
Result: John has attempted this year 50 passes.