Sue's Sushi placed two orders with its fish supplier. One order was for 11 pounds of salmon and 6 pounds of tuna; the order totaled $191. The other order was for 8 pounds of salmon and 4 pounds of tuna; this order totaled $136. What is the cost for one pound of salmon and one pound of tuna?

For this question you’ll want to make it into a simultaneous equation so it would be

11s+6t = 191

8s+4t = 136

Now you need to make either t or s the same on both equations, do this by finding a common multiple. In this instance I’d make t the same.

So it would be:

22s+12t=382

24s+12t=408

You can then take 12t from each equation:

22s=382

24s=408

So:

2s=26

S=13

Then substitute s into an earlier equation to find t:

(13x8) + 4t = 136

104+4t=136

4t=32

t=8

So, t=8 and s=13