Goldfish and mollies

Question

A fish take it contains 1/2 as many goldfish as mollies, and there are 6 more guppies then goldfish. If the total combined number of fish in the tank is 22. How many mollies are in the tank?

Answer 1

HI Aneila!

1. Assign each group a letter

Goldfish = F

Guppies = G

Mollies = M

2. Create equations defining each group

Eq 1: F = M÷2

Eq 2: G = F + 6

Eq 3: F + G + M = 22

3. Plug in Equations 1 into 2

G = F + 6

G = (M/2) + 6

3. Plug in Equation 1 and new equation into 3

F + G + M = 22

(M/2) + [(M/2) + 6] + M= 22

2M + 6= 22

2M = 22 - 6

4. Solve for M

Answer 2

Hello Aneila,

Let G1= Number of gold fish

M= Number of mollies

G2 = Number of guppies

given

G1 = M/2.... Eq 1

G2= 6+ G1 = 6 +M/2... Eq 2

Also G1 +G2 + M = 22... Eq 3

Plug in Eq 1 and Eq 2 in Eq 3

M/2 +6+ M/2 + M =22

2M = 22- 6

Get M from here ( Number of mollies)