Un trunchi de piramidă triunghiulară regulată are înălțimea egală cu 12 cm apotema bazei mari egală cu 6 cm şi apotema bazei mici egală cu 4 cm. Calculați înăltimea piramidei din care provine trunchiul şi lungimea apotemei trunchiului de piramidă.

Anyone know? will mark brainliest if you're correct!

If m∠abc = 70°, what is m∠abd? justify your reasoning.  using the addition property of equality, 40 + 70 = 110, so m∠abd = 110°.  using the subtraction property of equality, 70 − 30 = 40, so m∠abd = 30°.  using the angle addition postulate, 40 + m∠abd = 70. so, m∠abd = 30° using the subtraction property of equality.  using the angle addition postulate, 40 + 70 = m∠abd. so, m∠abd = 110° using the addition property of equality.

The sum of the speeds of two trains is 720.2 mph. if the speed of the first train is 7.8 mph faster than the second train, find the speeds of each.