Siti has $x$ number of $5 notes. Aisha has $y$ number of $2 notes. They have a total of 30 notes with total value $111. Form and solve two simultaneous equations to calculate the amount of money Siti has. Answer $...

1. Form equations for the total number of notes and the total value of the notes.

Since Siti has $x$ $5 notes and Aisha has $y$ $2 notes,

$x+y=30$

For the total value,

$5x+2y=111$

2. Eliminate one variable to find the number of \$5 notes Siti has.

From $x+y=30$,

$2x+2y=60$

Subtract this from $5x+2y=111$:

$5x+2y-(2x+2y)=111-60$

$3x=51$

$x=17$

3. Calculate the amount of money Siti has.

Siti has $17$ notes of $5 each.

$17\times 5=85$