=
⨯
=
(
x
+
y
)
⨯
(
a
+
b
)
=
ax
+
ay
+
bx
+
by
=
(
⨯
)
+
(
⨯
)
+
(
⨯
)
+
(
⨯
)
=
x=
50
y=
50
a=
47
b=
48