K=9S/2, total savings is S+9S/2=11S/2. So 9S/2÷11S/2=9/11. (a) The ratio is 9:11.
(b) Kieran’s savings are 9/11 of the total savings.
(c) Simon’s savings are S÷11S/2=2/11 of total savings (or simply subtract 9/11 from 1).
(d) K-S=28, 9/11-2/11=7/11 of the total savings, so 7/11 of the total savings is $28 and total savings is 11/7×28=$44.
CHECK
Kieran has 9/11 of $44 which is $36 and Simon has $8. 36/8=9/2 so the ratio is correct.
Simon has $28 less than Kieran and 36-8=28, which is correct.