Answer:23 mm
Step-by-step explanation:
add both 15 and 8 because they are as long as the one on the bottom
Answer:
70
find the small unknown side by subtracting the two sides across from it. 12-7=5. add the 15 and 8 for the big unknown side. 15+8=23. add all the sides. 12+15+7+8+5+23=70
