Answer:
y=10 ( number of acrobat)
Step-by-step explanation:
let x be the elephant and y the acrobat
elephant has 4 legs and acrobat 2
4x+2y=40
x+y=15 ⇒x=15-y
substitute for x in the equation:
4(15-y)+2y=40
60-4y+2y=40
-2y=40-60
y=-20/-2
y=10 ( number of acrobat)
number of elephant=15-10=5 elephants