解:設(shè)蘋(píng)果樹(shù)有x棵,杏樹(shù)有
x棵,梨樹(shù)的棵數(shù)是
x棵,
x+
x+
x=319,
x=319,
x=319
,
x=319×
,
x=132,
杏樹(shù):
x=
×132=88(棵),
梨樹(shù):
x=
×132=99(棵),
答:蘋(píng)果樹(shù)有132棵;杏樹(shù)有88棵;梨樹(shù)有99棵.
分析:設(shè)蘋(píng)果樹(shù)有x棵,則根據(jù)“杏樹(shù)和蘋(píng)果樹(shù)的比是2:3,”知道杏樹(shù)有
x棵;再根據(jù)“梨樹(shù)是蘋(píng)果樹(shù)的
,”知道梨樹(shù)的棵數(shù)是
x棵,再根據(jù)三種樹(shù)共319棵,列方程解決問(wèn)題.
點(diǎn)評(píng):解答此題的關(guān)鍵是設(shè)出未知數(shù),再根據(jù)題意用設(shè)出的未知數(shù)表示出其它的未知數(shù),最后根據(jù)題中的數(shù)量關(guān)系列出方程解決問(wèn)題.