let the goldfish be x and the guppies be y
4x + 3y = 29...equ(1)
3x + 5y = 30...equ(2)
multiplying equation 1 by 5 and equation 2 by 3
20x + 15y = 145...equ(1)
9x + 15y = 90...equ(2)
subtracting equation 2 from 1
11x = 55
∴x = 5
substituting the value of x into equation
4(5) + 3y = 29
20 + 3y = 29
3y = 9
∴y =3