6. Ziad has 26 money bills in his bank, some are 500 L.L. bills and some are 1000L.L.

1000 bills = 7

500 bills = 19

Step-by-step explanation:

x=number of 1000 bills

y= number of 500 bills

(you can even invert them, no problem)

the system is

x + y = 26

1000x + 500y = 16500

therefore

x=26-y

using this value in the next equation

1000*(26-y) + 500y = 16500

26000 - 1000y + 500y = 16500

-500y = - 9500

y=9500/500= 19

x=26-19= 7

Explanation with Proof is given below.

Step-by-step explanation:

Given:

In  Δ ABC,

m∠ A = 59°

m∠ B = 37°

In Δ A'B'C'

m∠ A' = 59°

m∠ C' = 84°

To Prove:

Δ ABC ~ Δ A'B'C'

Proof:

In  Δ ABC we have,

m∠ A + m∠ B + m∠ C = 180° {Angle Sum Property of Triangle}

Substituting the given values we get

Now,

In  Δ ABC and Δ  A'B'C'

∠ A ≅ ∠ A'     …………..{measure of each angle is 59°}

∠ C ≅ ∠ C'     ……….{measure of each angle is 84°}

Δ ABC ~ Δ A'B'C'  ….{ By Angle-Angle Similarity Postulate} Proved