Question 759117
4/5 + 7/8 = s/20 


32/40 + 7/8 = s/20 


32/40 + 35/40 = s/20 


(32 + 35)/40 = s/20 


67/40 = s/20 


67*20 = 40s

 
1340 = 40s 


1340/40 = s 


s = 1340/40


s = 67/2  <--- Answer as a fraction


s = 33.5  <--- Answer as a decimal