Don’t know how to do this so pls help:)

Divide 15 by 20 and then take that and multiply it by 16 and you'll get 12

when you have a problem like this and you need the smaller triangle measurements then the value from the smaller triangle will be on the top and if you need the larger triangle values then the larger value will be on top to find the ratios and multiply it by the other value from the denominator triangle

i need more information to answer