问3个数学题

the function f is defined for each positive three-digit integer n by f(n)=2^x3^y5^z, where x, y,and z are the hundreds, tens, and units digits of n,respectively. if m and v are three-digit positive integers such that
f(m)=9f(v), then m-v=?

怎么做?一点思路都没有.

if a and b are intergers ,is b even?

(1)3a+4b is even

(2)3a+5b is even

in the xy-plane, what is the x-intercept of a certain line?

(1) the line passes through the point (0,2)
(2) the y-intercept of the line is 2

什么是"x-intercept of a certain line"???  x到线的截距?