Multi step equations

Question

the lifespan of a guinea pig is 6 years less than that of a giraffe. The lifespan of a tiger is 4 times that of the guinea pig. If the total lifespan of the animals is 30 years, calculate the longevity for the giraffe.

Answer 1

Let's say the lifespan of the guinea pig= P, giraffe = G, and tiger = T

We know the following:

G - 6 = P (guinea pig is 6 years less than giraffe)

4*P = T

G + P + T = 30

So to find the lifespan of T we first need to look at out equation to see what we can solve for first. By looking at the equation we see that the first has P and G while the second had P and T. This means we can put G in terms of P as well as T in terms of P.

So we can say:

G = P + 6 and

T = 4*P

Now try plugging in these equations in place of G and T in the last equation.

So,

(P+6) + P + (4P) = 30

Simplify: P = 4

By using the value calculated you can also solve for T using the other equations.

Overall, for problems like this, first put the words into equations. This makes it easier to see how it could be solved. Then try to see if you can alter the other equations to put them in terms of some variable like we did for the first two equations. This makes it easier to plug in place of the variables and simplify equations like we did above. Hope this helps you!