Let us assume the number of turtles = x
Then
Number of frogs = x + 4
Number of crayfish = 2x + 3
Total number of turtles and crayfish = 54
Then we can write the equation as
x + 2x + 3 = 54
3x + 3 = 54
3x = 54 - 3
3x = 51
x = 51/3
= 17
Then
The number of frogs = x + 4
= 17 + 4
= 21
So there are 21 frogs in the pond that has been counted by Ramon.
9/20 is greater
9/20 = 0.45
..............
2.8y + 6 + 0.2y = 5y - 14
(Simplify like terms in first half of equation)
3y + 6 = 5y - 14
(Subtract both sides by 3y)
6 = 2y - 14
(Flip)
2y - 14 = 6
(Add both sides by 14)
2y = 20
(Divide both sides by 2)
y=10
The Muslim mathematicians adopted a numerical system from India. The correct answer is B.