5.小明和爸爸的年龄和是45岁,小明的年龄是爸爸的$\frac{1}{4}$,设爸爸的年龄为x岁,列方程错误的是( )
| A. | x+$\frac{1}{4}$x=45 | B. | $\frac{1}{4}$x=45 | C. | (1+$\frac{1}{4}$)x=45 |
4.甲数比乙数多$\frac{1}{3}$,如果甲数是20,求乙数列式子为( )
0 161064 161072 161078 161082 161088 161090 161094 161100 161102 161108 161114 161118 161120 161124 161130 161132 161138 161142 161144 161148 161150 161154 161156 161158 161159 161160 161162 161163 161164 161166 161168 161172 161174 161178 161180 161184 161190 161192 161198 161202 161204 161208 161214 161220 161222 161228 161232 161234 161240 161244 161250 161258 199269
| A. | 20÷(1-$\frac{1}{3}$) | B. | 20÷(1+$\frac{1}{3}$) | C. | 20×(1+$\frac{1}{3}$) |