A 16-inch board is to be cut into three pieces so that the second piece is twice as long as the first plece and the third piece is 5 times as long as the first piece. If x represents the length of the first piece, find the lengths of all three pieces.
What is the length of the first piece?

if the pieces are longer than each other then

x=5x+2x will be equal 7x

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this

94

step-by-step explanation:

average the numbers and use a variable to figure out the minimum to get a 90.

(79+94+91+92+x)/5=90

x = 94