David scored x marks for his mathematics test, Edwin scored 4/5 of what David scored. Frank scored 38 marks more than Edwin and Gabriel scored 5 fewer marks than Frank.(a) Express Gabriel's marks in terms of x.(b) if the average mark of the four boys is 64.5, find Gabriel's marks for the Mathematics test.
Accepted Solution
A:
D=xE=(4/5)•xF=E+38F=(4/5)•x+38G=F-5G=(4/5)x+38-5G=(4/5)x+33. ⟨——answer for A 64.5=[d+e+f+g]/4 64.5=[5x/5+4x/5+4x/5+38+4x/5+33]/44•64.5=9x/5+8x/5+71 258=17x/5+71258-17=17x/5 241=17x/5 5•241=17x1205/17=x 70.88=xG=(4/5)x+33G=(4/5)(70.88)+33G=89.7 ⟨——answer to part B