
AX  = b or  [tex]\left[\begin{array}{cc}1&1\\0.1&0.05\end{array}\right] \left[\begin{array}{c}x\\y\end{array}\right] = \left[\begin{array}{c}15\\1.10\end{array}\right][/tex]
Step-by-step explanation:
Here, total number of coins  = 15
Let us assume the number of dimes  = x
Also, let us assume the number of nickels  = y
So, x + y = 15 Â .... (1)
Again, 1 dime  = $0.1
So, x dimes  = x ($0.1)  = $ (0.1 x)
1 nickel  = $0.05
So, y nickels  = y ($0.05)  = $ (0.05 y)
Also, total value of coins  =  $1.10
⇒  0.1 x + 0.05 y  = 1.10   .... (2)
So, from (1) and (2) the matrix can be written as:
AX  = b or  [tex]\left[\begin{array}{cc}1&1\\0.1&0.05\end{array}\right] \left[\begin{array}{c}x\\y\end{array}\right] = \left[\begin{array}{c}15\\1.10\end{array}\right][/tex]
The above matrix can be used to determine the number of dimes  x and  nickels y.