8. Given ^- -f | = Y, and ^ + | = 8, to find the

CO U.J

values of x and 2/. Ans. a; = 6 ; y = 12.
9. Given a; -1-2^=17, and 3 a; — y=2, to find the
values of x and y. Ans. a; = 3 ; y = 1.
10. Given - — y ^ 1, and x — | = 8, to find the
values of x and y. Ans. sc = 10 ; y = 4>

11. Given^ + ^=0„and^+^^ = l,
to find the values of x and y. Ans. a; = 4 ; y = 6..
12. Given ^^^ + 6y = 21, and ?^ = 23 — 5 a:, to
find the' values of x and y. Ans. a; = 4 ; y = 3.
CASE IL

173. To eliminate by substitution.
1. Given a; + 2^ = 17, and 3 a; — y = 2, to find the
values of x and y.
SIMPLE EQUATIONS. 141

OPERATION. By transposing- 2y in equa-

a; + 2y= It (I) *'°° ^^^' ^® ^^^® equation

- ^ ■' (3), which gives the value

"^ ~" w of a; expressed in terms ofy.
a; = lY — 2y (3) Substituting this value of x,

3(11 — 2y) — y= 2 (4) or 17 — 2 2^, for a; in equa-

61 — 1r/= 2 (5) tio° (2), we obtain (4), an

Tm= 49 Cgl equation with only one uii-

pt /hv known quantity, y. Reduu-

^= It- 14 (8) ^g.-ehave(7),or,= 7.
'' ' substituting, now, 7 for y in

^ C^J equation (3), and reducing,

we have (9), or a; = 3.
