exam Maths Puzzle Numerical Ability

AHHH! I need help with this one. I am so confused when it comes to matrices and now adding letters too???

Encoding matrix A = [3 5 (top)
1 2 (bottom)]
C

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exam Other Question

1st sum of money at 6%
2nd sum of money is twice the first sum + $1000 at 10% and the total annual income is $620..

how much is invested at each rate and how did you get it.. this has to be done in the i=prt form Find

8b(1.7f)