Can someone help with numbers 1 and 2 for both of them tell me the answer and how you get it please I need the two of them do not send me link just write please do not send me link please

Answer:
a = 20m
b = 8ft
Step-by-step explanation:
a² = 25² - 15²
a² = 625 - 225
a² = 400
a = 20m
b² = 10² - 6²
b² = 100 - 36
b² = 64
b = 8ft