Answer:
For ²⁴Mg
1. Proton number = 12
2. Neutron number = 12
For ⁸⁸Sr:
1. Proton number = 38
2. Neutron number = 50
Step-by-step explanation:
For ²⁴Mg:
1. Determination of the number of proton. 
The atomic number of an element is simply defined as the number protons in the atom of the element. The atomic number of ²⁴Mg is 12 since no two elements have the same atomic number.
Atomic number = 12
Proton number = Atomic number
Proton number = 12
2. Determination of the Neutron number. 
Mass number = 24
Proton number = 12
Neutron number =? 
Mass number = Proton + Neutron 
24 = 12 + Neutron 
Collect like terms 
Neutron = 24 – 12
Neutron number = 12
For ⁸⁸Sr:
1. Determination of the number of proton.
The atomic number of ⁸⁸Sr is 38.
Atomic number = 38
Proton number = Atomic number 
Proton number = 38
2. Determination of the Neutron number. 
Mass number = 88
Proton number = 38
Neutron number =? 
Mass number = Proton + Neutron 
88 = 38 + Neutron 
Collect like terms 
Neutron = 88 – 38
Neutron number = 50