Math question :)

Question

Bookshelf has 433 books, the second shelf has 23 books more than the first one, the third shelf has 33 books less than the second one and the fourth one has 2 times more books than the third one. How many books are on each shelf ?

Answer 1

S=23+F

T=S-33

Fth = 2T = 2S-66

F+S+T+Fth = 433

S-23 +S + S-33 + 2S-66 = 433

5S = 555

S = 555/5= 111 on 2nd shelf

T=111-33 = 78 on 3rd shelf

Fth = 156 on 4th shelf

F = 111-23 = 88 on 1st shelf

88+111+78+ 156 = 433