Prove 24|2*7^n+3*5^n-5

I showed true for n=1:

2*7+3*5-5=14+15-5=24

Thus divisible by 24

Assume true for all k>=1. Need to prove true for n=k+1

Then 2*7^(k+1)+3*5^(k+1)-5=14*7^k+15*5^k-5

I get this far and now I get stuck simplifying enough to show it's true.