12/7 + 8/7
12+8 = 20
20/7 = 2 and 6/7ths
Just look it up on the web that will help a lot
I think the fourth option is the answer. It wi give you the Side angle side postulate.
.944
2 1/9 = 2.111
7/6 = 1.167
2.111-1.167= .944
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