Step-by-step explanation:
Value from:
1 shilling coins
=
1
(
21
−
3
x
)
=
21
−
3
x
5 shilling coins
=
5
(
2
x
)
=
10
x
10 shilling coins
=
10
(
x
)
=
10
x
Total value
=
72
shillings
i.e.
21
−
3
x
+
10
x
+
10
x
=
72
shillings
−
3
x
+
10
x
+
10
x
=
72
−
21
17
x
=
51
x
=
51
17
x
=
3
∴
Mary has
3 10
shilling coins.
