we have
tanA=7/24
tanA= opposite side/ adjacent side
by pythagorus theorem;
hypotenuse^2= opposite^2 + adjacent^2
that is,
hypotenuse^2= 7^2+ 24^2
=625
therfor hypotenuse= sq.root(625)=25
now
sinA= opposite/hypotenuse= 7/25
cosA=adjacent/hypotenuse= 24/25
sinA+cosA = 7/25 + 24/25
= 31/25