Answer:
[tex]b = \frac{4y}{5l + 5s} [/tex]
Step-by-step explanation:
[tex] \frac{4y}{5b} = l + s[/tex]
multiplying through by the L.C.M. which is 5b
[tex] \frac{4y}{5b} \times 5b = (l + s) \times 5b[/tex]
cancel out
4y =5bL+ 5bs
factorizing b out
4y=b ( 5L +5s ).
making be the subject by dividing through by ( 5L+ 5s )
[tex] \frac{4y}{5l + 5s} = \frac{b(5l + 5s)}{5l + 5s} [/tex]
[tex]b = \frac{4y}{5l + 5s} [/tex]