计算:
(1)﹣t3•(﹣t)4•(﹣t)5;
(2)(b2n)3(b3)4n÷(b5)n;
(3)tm+1•t+(﹣t)2•tm(m为整数);
解:(1)原式=﹣t3•t4•(﹣t5)=t3+4+5=t12;
(2)原式=b6n•b12n÷b5n=b18n÷b5n=b13n;
(3)原式=tm+2+t2+m=2t2+m
0.7x=0.044.8
则x=____