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.

D=x

E=(4/5)•x

F=E+38

F=(4/5)•x+38

G=F-5

G=(4/5)x+38-5

G=(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]/4

4•64.5=9x/5+8x/5+71

258=17x/5+71

258-17=17x/5

241=17x/5

5•241=17x

1205/17=x

70.88=x

G=(4/5)x+33

G=(4/5)(70.88)+33

G=89.7 ⟨——answer to part B

0.6, 3/5, and 6% are the 3 same portion.

but, when they're all changed to a decimal they would equal to 0.6.

hope this , good luck!

it would take 7/10 of an hour too fill the pool.

step-by-step explanation: