When using a calculator or long division, you should find that
7/9 = 0.7777...
where the 7s go on forever
So we can say that 7/9 = 0.777 approximately. You could argue that the last '7' would round up to an '8' and we could say 7/9 = 0.778; however, I'll stick to the first value so that it matches with the answer.
Since 7/9 = 0.777, this means 2 & 7/9 = 2 + 7/9 = 2 + 0.777 = 2.777 which is box A.
X=Marks sister's age x+11= Marks age x+11 +8 = 2x+8 x+19=2x +8 x+19-x=2x-x +8 19-8=x+8-8 11=x Marks sisters age in 8 years 11-8= 3 Marks sisters age now x+11=22 Marks age in 8 years 22-8= 14 Marks age now