To solve this problem, we'll apply the properties of division:
- Step 1: Start with the given equation:
x:70=1.
- Step 2: Recognize that in order to achieve the result of 1 from a division, the number being divided must be equal to the divisor.
- Step 3: Use the property of division, which states that dividing any number by itself results in 1.
Hence, if x÷70=1, then x=70.
Therefore, the solution to the equation is 70, meaning the missing number in the equation ?:70=1 is x=70.