Using the Pythagorean theorem:
c = sqrt(8^2 + 7^2)
c = sqrt(64 + 49)
c = sqrt(113)
c = 10.6
There is no y in this question, however we can solve for t.
1.4t - 0.4(t - 3.1) = 5.8
1.4t - 0.4t + 1.24 = 5.8
t + 1.24 = 5.8
t = 4.56
To find the total distance, Divide distance already walked by percentage:
8 / 0.55 = 14.55 km
She already walked 8 so now subtract:
14.55 - 8 = 6.55 km left to walk
2(3-4a) + 5(a-7) first do the distributive property
6-8a + 5a-35 now combine like terms
-41 - 3a is the final answer