1. Max bought 5 notebooks and 4 pens. He spent a total of $10.65. Emily bought 3 notebooks and 3 pens for a total of $7.50. How much did the notebook and pens cost each.

2. Mr. Smith inherits $45,000. He invests part of the money into mutal funds giving him 4% return, and he invests the other part at the stock markets giving him 6%. At the end of the year he earned $2430 of interest. How much did he invest in both accounts?

1. This is what I did.

=====>your first part is ok
-3(5n+4p=10.65)

4(3n+3p=7.50)

-15n -12p= -31.95

12n +12p= 30.00

----------------------------------------------
-3

n/3

= 1.95/3

n=.65 (The cost of one notebook) Substitute n=.65 into 1st equation: * (The cost of one pen) --------------------------------------------------------------
-15n -12(.65) -31.95

===>this is where you went South. You substituted the value you found for n into p. See * above.
-15n - 7.80 - 31.95 I added 7.80 and divided by -15

N=1.61 P=.65

What did I do wrong?

I have no idea on # 2.