How can you tell if a triangle has no congruence theorem?

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

What is the volume of the cone to the nearest cubic millimeter? (use π  = 3.14) a) 46 mm3 b) 128 mm3 c) 183 mm3 d) 275 mm3 diameter = 5 mm height = 7 mm how do you do this problem step by step?

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year. the population of her town is changing by a constant rate. true or false?